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Biomedical subjects

R H Miller

Publications and source records attributed to R H Miller.

At least 91 records · Page 5Linked to original sources
PubMed1996

Competition in the health system: good news and bad news.

Competition among health plans, hospitals, and physicians has taken place in fifteen health care markets primarily on the basis of price and secondarily on network breadth and style of care. In most markets, competition resulted in lower (or slowly growing) premium prices. Within a type of plan product, competition was leading to similar prices and networks and was reducing product differentiation among health plans. Competition was not taking place on the basis of measured and reported quality of care, which limited the capacity of employers and enrollees to make informed health plan choices. As a result, there was a substantial gap between competition as envisioned by the architects of the managed competition model and competition as it is evolving today.

Community Health Planning↗
PubMed1996

Health system integration: a means to an end.

The creation of integrated firms and contractual networks in health care often is a precondition for other forms of integration that could actually lower costs and improve quality of care. Although different types of integration activities are leading to innovations in the production of services and the care of populations, the continued influence of the "old" indemnity insurance/fee-for-service system creates important obstacles to those integration activities. If creation of integrated firms and contractual networks races ahead of other forms of integration, it could produce uncompetitive markets that reduce pressures to integrate in ways that can cut costs and improve quality of care. Purchasers' actions could play a major role in determining the future of various integration activities.

Community Health Planning↗
PubMed1996

Comparison of milk and blood lipids in Jersey and Holstein cows fed total mixed rations with or without whole cottonseed.

Lipids in milk and blood were examined in Holstein and Jersey cows (8 lactating and 4 dry) fed two TMR containing either 10% whole cottonseed or a control concentrate mixture of corn, cottonseed hulls, and cottonseed meal in a switchback experiment. Milk from Jersey cows contained more total lipid than did milk from Holstein cows (4.4 vs. 3.5 g/dl), had a higher proportion of lipid as triglyceride (97.3% vs. 96.7%), and had a lower proportion of lipid as phospholipid (0.8% vs. 1.0%). Milk from the group fed cottonseed contained fewer medium-chain fatty acids (24.4% vs. 29.4%) and more C18 fatty acids (35.9% vs. 25.8%) than did milk from the control group. Total blood lipids were 234 mg/dl for Holsteins and 168 mg/dl for Jerseys. Total blood lipids were higher for dry cows fed cottonseed (100 vs. 72 mg/dl), particularly Jersey cows. As determined by gravimetric or TLC analysis, milk fat percentages of cows fed cottonseed were not different from those of cows fed control rations. However, as determined by infrared instrumentation, milk fat appeared to be lower (4.3%) for cows fed cottonseed than that (4.6%) for control cows. Changes in milk fatty acids that were related to diets might explain the difference between infrared and gravimetric determinations of milk fat.

Animal Feed↗
PubMed1996

Reactivity of purified complement component 3b with bovine neutrophils and modulation of complement receptor 1.

OBJECTIVE: To study binding of purified complement component C3b to bovine blood and mammary neutrophils (PMN) after various treatments and determine their ability to modulate receptor numbers. DESIGN: Cell isolation, activation, and flow cytometric studies. ANIMALS: Healthy lactating Holstein cattle. PROCEDURE: Complement component C3b (18,300 kd) was isolated from bovine serum by column chromatography, and flow cytometric assays using fluorescein isothiocyanate-labeled C3b were developed to evaluate binding to PMN complement receptor 1. Multiple substances were tested to determine their overall effect on C3b binding to PMN. Blood and milk PMN were isolated by differential centrifugation and exposed to optimal concentrations of recombinant human C5a, formyl-methyl leucyl phenylalanine, recombinant bovine interferon-gamma, variable concentrations of phorbol myristate acetate (0.01 to 100 ng), calcium ionophore A23187, serum-opsonized zymosan, zymosan-activated serum (ZAS), zymosan-activated plasma (ZAP), and hydrocortisone acetate (25 and 70 ng). Additionally, mammary and blood PMN were preincubated in skim milk and whey. RESULTS: Variable concentrations of phorbol myristate acetate caused a dose-dependent increase in percentage of PMN binding C3b, and increased the amount of C3b bound per cell. Significant increases were observed after PMN treatment with calcium ionophore, serum opsonized zymosan, ZAS, and ZAP; conversely, incubation of PMN with hydrocortisone acetate resulted in reduced overall binding of C3b. Mammary PMN consistently bound more C3b, which was attributed to their activation during migration into the mammary gland. Binding of C3b was inhibited by skim milk. Activation of blood PMN with PMA, ZAS, and ZAP elicited larger responses than those observed for mammary PMN. CONCLUSIONS: Modulation of complement receptors on bovine PMN is possible. Additionally, significant difference between the level of binding of C3b to blood and milk PMN, with milk PMN having higher binding, may be attributable to migration of PMN into the mammary gland, causing increased receptor expression. CLINICAL RELEVANCE: Contribution to a greater understanding of the role of complement in bovine immunologic systems, leading to testing for in vivo enhancement of bovine immune responses to invading pathogens.

Animals↗
PubMed1996

Intramammary defense against infections induced by Escherichia coli in cows.

OBJECTIVE: To examine Escherichia coli lipopolysaccharide (LPS) effects on expression of CD14 and CD18 cell surface receptors and lectin/carbohydrate-mediated nonopsonic phagocytosis of E coli. DESIGN: Cell isolation, monoclonal antibody, phagocytosis, and flow cytometric studies. ANIMALS: 4 clinically normal lactating Holstein cows for studies on CD14 and CD18, and 2 for phagocytosis studies. PROCEDURE: Binding of CD14 and CD18 monoclonal antibodies to blood and milk neutrophils and mononuclear leukocytes was studied by flow cytometry before and after intramammary injection of LPS, and nonopsonic phagocytosis of E coli by blood neutrophils was determined. Presence of intracellular CD14 was determined after in vitro incubation of neutrophils in skimmed milk and after fixation and permeabilization of freshly isolated neutrophils. RESULTS: Before LPS injection, percentages of blood neutrophils and large mononuclear (LMO) cells expressing CD14 averaged 3 and 63% and 68 and 35% for mammary neutrophils and LMO cells, respectively. After LPS injection, CD14 was only detected on blood and mammary LMO cells (61 and 25%); receptor expression increased by 1.8- and threefold, respectively. In vitro incubation of neutrophils in skimmed milk increased the percentage of neutrophils expressing CD14. The number of blood neutrophils staining positive for CD14 increased after permeabilization of the plasma membrane, which was blocked by unlabeled anti-CD14 monoclonal antibodies. Before LPS, percentages of blood neutrophils and LMO cells expressing CD18 averaged 93 and 95% and was 88 and 55% for mammary neutrophils and LMO cells, respectively. After LPS, percentages of mammary neutrophils and LMO cells expressing CD18 increased to 100 and 95%, respectively. Expression of CD18 was 2.6-fold higher for mammary neutrophils before injection of LPS, compared with blood neutrophils, either before or after LPS. In absence of opsonins, neutrophils with adherent and phagocytosed E coli averaged 83 and 14%. CONCLUSIONS: LPS modulated expression of CD14 and CD18 and lectin-carbohydrate interactions mediated nonopsonic phagocytosis of E coli. An intracellular pool of CD14 exists in bovine neutrophils and is capable of translocating to the cell surface. CLINICAL RELEVANCE: Development of methods to maximize expression of CD14 receptors on mammary neutrophils involved in production of tumor necrosis factor-alpha, and nonopsonic phagocytosis could result in reducing prevalence of mastitis in dairy cows.

Animals↗
PubMed1996

Acute laryngeal trauma.

Although laryngeal trauma is a rare injury, over the past 30 years several authors have reported their experience. Methods of evaluation and treatment are discussed as well as controversial aspects of patient management. The treatment varies with the extent of injury but consists of either conservative, nonsurgical management or surgical reduction. A delay in the early detection of laryngeal trauma may develop into life-threatening airway problems; therefore prompt diagnosis should be followed immediately by skillful airway management.

Humans↗
PubMed1996

Congenital midline nasal masses: dermoids, gliomas, and encephaloceles.

Congenital midline nasal masses are rare entities and therefore easily misdiagnosed or missed altogether. This article reviews the three most common congenital midline nasal masses: dermoids, gliomas, and encephaloceles. Discussion entails embryology, diagnosis, radiologic workup, surgical therapy, and complications.

Dermoid Cyst↗
PubMed1995

Characterization of a novel oligodendrocyte cell surface molecule.

Cell-type-specific reagents have proven useful in the analysis of central nervous system (CNS) development and function. Most markers of oligodendrocytes are components of myelin sheath, which in the CNS is the specific product of oligodendrocytes. We have isolated a novel monoclonal antibody termed 2B10 which was raised against embryonic rat spinal cord tissue. In adult rat cerebrum, cerebellum, and spinal cord, 2B10 immunoreactivity is predominantly localized in white matter. 2B10 immunoreactivity is absent from peripheral nerve, suggesting that in the nervous system the 2B10 antigen is restricted to the CNS. Dissociated cell culture studies indicate that 2B10 labels a cell surface molecule, and its cellular distribution is coincident with O1 and myelin basic protein-positive oligodendrocytes. By contrast, 2B10 does not label GFAP-positive astrocytes. These data suggest that in the CNS the 2B10 antigen is expressed specifically on oligodendrocytes. Biochemical analysis indicates that 2B10 recognizes a protein with an apparent molecular weight of approximately 79,000 in reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Developmentally, 2B10 immunoreactivity is detectable in rat spinal cord at as early as embryonic day 14. The relative abundance of this molecule decreases during myelination, but is maintained at a sustained level throughout adulthood. The 2B10 antigen appears not to be a myelin-associated protein since it is not detected in purified myelin fractions. 2B10 immunoreactivity is not detectable in extracts of rat sciatic nerve, heart, kidney, muscle, and skin, but is detectable in extracts of spleen and thymus. These data suggest that the 2B10 antigen is a novel cell surface molecule that is expressed on oligodendrocyte lineage cells throughout development.

Animals↗
PubMed1995

Estimating health expenditure growth under managed competition. Science, simulations, and scenarios.

The estimated impact of health system reform proposals on health expenditures influences the health system reform debate. Health expenditure growth rate (HEGR) estimates are particularly critical because small differences in rates over time create large differences in health expenditures. There currently is no hard scientific basis for estimating the impact of managed care/managed competition legislation and market developments on the HEGR. For the 1994 health system reform debate, the two leading nonpartisan modelers developed qualitative scenarios about future health system developments in which managed care/managed competition would have little or no impact on the HEGR. We conclude that there are alternative plausible scenarios, based on current health system changes interacting with potential legislation, in which managed care/managed competition will substantially lower the HEGR. We recommend that simulation models should provide a range of estimates that better reflect both market trends and the profound uncertainty about the effects of health system reform.

Competitive Medical Plans↗
PubMed1995

Asynchronous differentiation of clonally related spinal cord oligodendrocytes.

Oligodendrocytes are responsible for myelination in the vertebrate central nervous system, but what controls their differentiation remains unknown. To determine if clonally related rat spinal cord oligodendrocyte precursors differentiated synchronously in a complex environment, retroviral clonal analysis was combined with immunocytochemistry using antibodies which define consecutive stages in oligodendrocyte development. In embryonic spinal cord cultures, most oligodendrocyte clones contained both differentiated oligodendrocytes and their precursors, demonstrating that clonally related oligodendrocytes differentiated asynchronously. Such asynchronous differentiation did not simply reflect differences in proliferation between clonally related cells. In young cultures, most clones were composed entirely of dividing cells. In older cultures, most clones contained nonproliferating immature precursor cells, suggesting that oligodendrocyte proliferation and differentiation are independently regulated, and differentiation is primarily regulated by environmental factors.

Animals↗
PubMed1995

Genetic heterogeneity of hepatitis C virus: quasispecies and genotypes.

Worldwide, HCV is a major etiologic agent of chronic hepatitis that may lead to the development of liver cirrhosis and hepatocellular carcinoma. Thus, significant morbidity and mortality is caused by HCV infection and effective control measures against the spread of this virus are needed. Originally, the extent of genetic heterogeneity of HCV was not fully appreciated. However, the breadth of the genetic heterogeneity of HCV is great, and this may have important implications in diagnosis, pathogenesis, treatment, and vaccine development. In an infected individual the HCV genome population circulates as a quasispecies distribution of closely related yet heterogeneous RNA sequences centered around one dominant sequence. The dominant sequence, as well as the consensus sequence, changes sequentially during the course of the infection. A hypervariable region (HVR1) within one of the envelope proteins of HCV (E2) evolves very rapidly. Patients infected with HCV mount a humoral immune response to epitopes of HVR1. However, sequential changes in the consensus sequence of HVR1 during infection result in the generation of variants that are not recognized by preexisting antibodies. This might represent a mechanism by which HCV evades host immune surveillance and establishes and maintains persistent infection. It will be important to determine whether HVR1 of HCV, as was found for the V3 loop of HIV, contains epitopes that elicit neutralizing antibodies against HCV. Furthermore, it will be important to determine whether the quasispecies nature of HCV helps the virus evade the cytotoxic T-cell response of the host. Analysis of complete or partial HCV genomic sequences revealed that HCV exists as multiple, distinct genotypes. A total of nine major genetic groups and at least 30 subgroups have been recognized. To evaluate the current classification of HCV genotypes, we performed phylogenetic analyses of complete and partial nucleotide sequences from isolates that represent all published variants of HCV. Analysis of complete HCV sequences, which represent three major genetic groups, supports the currently used genotype classification scheme. However, analysis of the partial genomic regions (ie, C, E1, and NS5b) of HCV isolates that represent all recognized variants of HCV demonstrates that the genetic relatedness among some of the genotypes was not equivalent in the different gene regions. Furthermore, the distinction among isolates, subtypes, and types of HCV was not always clear. This finding might reflect the shortcomings of analyzing only limited gene regions or may reflect the wide spectrum of genetic variation of HCV.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Development of glial cytoarchitecture in the frog spinal cord.

The origin of astrocytes and oligodendrocytes in the frog spinal cord, and the factors that regulate their differentiation are currently unknown. To determine the timing and pattern of glial cell differentiation, spinal cord sections from Xenopus at different developmental stages were labeled with antibodies specific for astrocytes and oligodendrocytes. Initially, radially oriented glial cells are present in all spinal cord quadrants and their processes contain similar levels of GFAP+ intermediate filaments in both gray and white matter. These cells then appear to differentiate directly into regionally specialized radially oriented astrocytes. Oligodendrocytes labeled with the 'Olig' antibody, however, are first detectable in the ventral quadrant. Differentiation subsequently occurs in a ventral-to-dorsal sequence beginning at the interface between the gray and white matte. These data suggest that the origin and regulation of Xenopus astrocyte and oligodendrocyte differentiation are distinct.

Animals↗
PubMed1995

Second primary malignancies in the head and neck cancer patient.

With improvements in locoregional control, the problem of second primary malignancies is rapidly being pushed to the forefront of head and neck oncology. While the constant long-term risk for the head and neck cancer patient has been well established, efforts at prevention, early detection, and treatment have been somewhat futile. Recent advances in genetic predisposition, biomarkers, photodiagnostic imaging, and differentiation therapy may soon offer improved outcomes. The literature is reviewed and current research is presented regarding the history, epidemiology, etiology, diagnosis, and treatment of second primary malignancies.

Carcinoma, Squamous Cell↗
PubMed1995

Early development and dispersal of oligodendrocyte precursors in the embryonic chick spinal cord.

Oligodendrocytes, the myelinating cells of the vertebrate CNS, originally develop from cells of the neuroepithelium. Recent studies suggest that spinal cord oligodendrocyte precursors are initially localized in the region of the ventral ventricular zone and subsequently disperse throughout the spinal cord. The characteristics of these early oligodendrocyte precursors and their subsequent migration has been difficult to assay directly in the rodent spinal cord due to a lack of appropriate reagents. In the developing chick spinal cord, we show that oligodendrocyte precursors can be specifically identified by labeling with O4 monoclonal antibody. In contrast to rodent oligodendrocyte precursors, which express O4 immunoreactivity only during the later stages of maturation, in the chick O4 immunoreactivity appears very early and its expression is retained through cellular maturation. In embryos older than stage 35, O4+ cells represent the most immature, self-renewing, cells of the chick spinal cord oligodendrocyte lineage. In the intact chick spinal cord, the earliest O4+ cells are located at the ventral ventricular zone where they actually contribute to the ventricular lining of the central canal. The subsequent migration of O4+ cells into the dorsal region of the spinal cord temporally correlates with the capacity of isolated dorsal spinal cord to generate oligodendrocytes in vitro. Biochemical analysis suggests O4 labels a POA-like antigen on the surface of chick spinal cord oligodendrocyte precursors. These studies provide direct evidence for the ventral ventricular origin of spinal cord oligodendrocytes, and suggest that this focal source of oligodendrocytes is a general characteristic of vertebrate development.

Animals↗
PubMed1995

Head and neck surgery workforce in the year 2014.

The head and neck surgery workforce in the United States over the next 20 years is of significant interest to physicians, patients, and others. Using election to fellowship in the American Society for Head and Neck Surgery or the Society of Head and Neck Surgeons, or both, as the criteria for designation as a head and neck surgeon, a mathematical model was designed to project the growth of the head and neck surgery workforce through the year 2014. The current combined active membership of the two societies was analyzed to determine the impact of age distribution on this model. The paradigm assumes 30 new head and neck surgeons each year and includes the appropriate mortality rate for each cohort. Based on this model, the total number of head and neck surgeons should decrease slightly from 1109 in the year 1994 to 1028 in the year 2014. A steady-state supply of head and neck surgeons is therefore predicted.

Adult↗